/**
*************************************************
  Skrá: T203Sd4_3.java
  Höfundur: Ragnar Geir Brynjólfsson.
  Dagsetning: 15.7.2002.
  Sýnidæmi um útfærslu mengis.
*************************************************
*/
import java.util.*;
class MySet extends HashSet {
  public MySet() {
    super();
  }
  public void union (MySet m) {
    super.addAll(m);
  }
  public void intersect(MySet m) {
    super.retainAll(m);
  }
  public void subtract(MySet m) {
    super.removeAll(m);
  }
  public boolean myadd(Object o) {
    return super.add(o);
  }
  public boolean myremove(Object o) {
    return super.remove(o);
  }
  public boolean contains(Object o) {
    return super.contains(o);
  }
  public int size() {
    return super.size();
  }
  public boolean isEmpty(){
    return super.isEmpty();  
  }
  public String toString() {
    return super.toString();
  }
}
class T203Sd4_3 {
  public static void main(String[] innst) {
    MySet Sundlaug = new MySet();
    MySet Heiti_potturinn = new MySet();
    Sundlaug.myadd("Anna");
    Sundlaug.myadd("Jói");
    Heiti_potturinn.myadd("Sigga");
    Heiti_potturinn.myadd("Kalli");
    System.out.println("Sundlaug: " + Sundlaug.toString());
    System.out.println("Heiti potturinn: " + Heiti_potturinn.toString());
    Sundlaug.union(Heiti_potturinn);
    System.out.println("Sundlaug: " + Sundlaug.toString());
    Sundlaug.subtract(Heiti_potturinn);
    System.out.println("Sundlaug: " + Sundlaug.toString());
    Sundlaug.myadd("Gunna");
    Sundlaug.myadd("Hannes");
    System.out.println("Sundlaug: " + Sundlaug.toString());
    Sundlaug.myadd("Hannes");
    System.out.println("Sundlaug: " + Sundlaug.toString());
    System.out.println("Sundlaug: " + Sundlaug.toString());
  }
}